Conventionally, setting the air pressure of a tire of a vehicle to a proper state is one of the items which must be observed for safety traveling of the vehicle. For example, when the air pressure of a tire lowers, the blowout rate increases and a burst occurs in high-speed traveling of a vehicle and this may cause a serious accident.
Therefore, a driver must usually check the air pressure of a tire. To check the air pressure of a tire, the air pressure has been measured for each tire by pressing a pressure measuring instrument against a valve provided on the rim of a wheel.
However, it takes a lot of time to measure the air pressure of each tire as described above and moreover, measuring the air pressure is very difficult for female drivers who have suddenly been increased in recent years. Therefore, there is a problem that the number of accidents caused by an abnormal air pressure of a tire increases because a driver tends to neglect checking the air pressure of a tire though the driver must usually check the air pressure.
The present invention is made to solve the above problem and its object is to provide a monitor for the air pressure of a tire of a vehicle having a plurality of wheels such as four or six wheels, making it possible to easily check the air pressure of a tire.